Luminescent material

ABSTRACT

This invention relates to luminescent materials for ultraviolet light or visible light excitation containing lead and/or copper doped chemical compounds. The luminescent material is composed of one or more than one compounds of aluminate type, silicate type, antimonate type, germanate/or germanate-silicate type, and/or phosphate type. Accordingly, the present invention is a good possibility to substitute earth alkaline ions by lead and copper for a shifting of the emission bands to longer or shorter wave length, respectively. Luminescent compounds containing copper and/or lead with improved luminescent properties and also with improved stability against water, humidity as well as other polar solvents are provided. The present invention is to provide lead and/or copper doped luminescent compounds, which has high color temperature range about 2,000K to 8,000K or 10,000K and CRI over 90.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 11/024,722 filed on Dec. 30, 2004, and claims priority from and the benefit of Korean Patent Application No. 10-2004-0042397 filed on Jun. 10, 2004, all of which are hereby incorporated by reference for all purposes as if fully set forth herein. This application is related to U.S. patent application Ser. No. 11/024,702, filed on Dec. 30, 2004, now issued as U.S. Pat. No. 7,554,129.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to fluorescent materials containing rare earth elements and more particularly to such luminescent materials for exciting ultraviolet as well as visible light containing lead and/or copper doped compounds.

2. Description of the Related Art

Lead and copper activated materials are known for short wave excitation, e.g. from a low pressure mercury lamp, such as barium disilicate activated by lead (Keith H. Butler, The Pennsylvania State University Press, 1980, S 175, orthosilicate activated by lead (Keith H. Butler, The Pennsylvania State University Press, 1980, S. 181), akermanites activated by lead, or Ca-metasilicate activated by Pb²⁺.

Generally, the maxima of the emission bands of such lead activated phosphors are located between 290 nm and 370 nm at 254 nm excitation. Bariumdisilicate activated by lead is an U.V. emitting phosphor which currently is used in sun parlor lamps.

Lead has in the ground state ¹S₀ two outer electrons. The electron configuration of the ground state is d¹⁰s², so that the lowest excited state has d¹⁰sp configuration. The excited sp configuration has four levels, ³P₀, ³P₁, ³P₂ and ¹P₁, which can be achieved between 165.57 nm (³P₀) and 104.88 nm (¹P₁) in the free ion. Transitions between ¹S₀ and ¹P₁ excited level are allowed by all selection rules. While transitions between ¹S₀ and ³P₀ are only allowed with the lowest symmetry, transitions between ¹S₀ and ³P₁ as well as ³P₂ are allowed only under certain conditions. However, excitation between 180 and 370 nm has the same emission. Excitation with wavelength longer than 370 nm is not possible.

Otherwise, luminescent materials are known having lead as a host lattice component. Molybdate phosphors containing MoO₄ ²⁻ centers are described in Bernhardt, H. J., Phys. Stat. Sol. (a), 91, 643, 1985. PbMoO₄ shows at room temperature red emission with an emission maximum at 620 nm under photoexcitation at 360 nm.

However, such emission is not caused by lead itself. In molybdates the luminescence properties are not caused by the metal ion M²⁺ (M²⁺MoO₄ where M²⁺=Ca, Sr, Cd, Zn, Ba, Pb etc). Here, defect centers of MoO₄ ²⁻ ions coupled to O²⁻-ion vacancies seem to be the reason. Nevertheless, the Pb²⁺-ion influences the preferred emission properties because it stabilizes the host lattice.

As a familiar example, tungstates (Ca,Pb)WO₄ as mixed crystals have a strong green emission with high quantum output of 75% (Blasse, G, Radiationless processes in luminescent materials, in Radiationless Processes, DiBartolo, B., Ed. Plenum Press, New York, 1980, 287). Under 250 nm excitation PbWO₄ shows blue emission and under 313 nm excitation PbWO₄ has an orange emission band, which can be caused by Schottky defects or by impurity ions (Phosphor Handbook, edited under the Auspice of Phosphor Research Society, CRC Press New York, 1998, S 205).

Copper was used as a monovalent activator in orthophosphates (Wanmaker, W. L. and Bakker, C., J. Electrochem. Soc., 106, 1027, 1959) with an emission maximum at 490 nm. The ground state of monovalent copper is a filled shell 3d¹⁰. That is the level ¹S₀. After exciting the lowest excited configuration is 3d⁹4s. This configuration has two terms, ³D and ¹D. The next higher configuration, 3d⁹4p, gives 6 terms ³P°, ³F°, ³D°, ¹F°, ¹D° and ¹P°. The transitions between the ground state ¹S₀ and the ¹D or ³D are forbidden by parity or spin, respectively. In copper ions, the excitation to the crystal field levels of 4p terms are allowed. Emission will be got either by a direct return from the crystal field odd state to the ground state or by a combination of transitions first from the odd state to a crystal field level and after that a second transition from these ³D or ¹D state of the 3d⁹4s configuration to the ground state.

The ground state of bivalent copper has 3d⁹-configuration. That is the level ²D_(5/2). In the bivalent copper, one of the d-electrons can be excited to the 4s or 4p orbital. The lowest exciting configuration is the 3d⁸4s with two quartet terms ⁴F, ⁴P and four doublet terms, ²F, ²D, ²P and ²G without emission caused by forbidden transitions. The higher exciting configuration is the 3d⁸4p-configuration with four terms ⁴D°, ⁴G°, ⁴F°, and ⁴P°, where emission can occur.

Copper activated or co-activated sulphide-phosphors are well known and they are commercial used for cathode ray tubes. The green-emitting ZnS:Cu, Al (wherein, the copper is used as activator and Al is used as co-activator) is very important in CRT applications.

In zinc-sulphide phosphors, the luminescent materials can be classified into five kinds, depending on the relative ratio of the concentration of activators and co-activators (van Gool, W., Philips Res. Rept. Suppl., 3, 1, 1961). Here, the luminescent centers are formed from deep donors or deep acceptors, or by their association at the nearest-neighbor sites (Phosphor Handbook, edited under the Auspice of Phosphor Research Society, CRC Press New York, 1998, S. 238).

Orthophosphates activated by copper (Wanmaker, W. L., and Spier, H. L., JECS 109 (1962), 109), and pyrophosphates, alumosilicates, silicates, and tripolyphosphates all activated by copper are described in “Keith H. Butler, The Pennsylvania State University Press, 1980, S. 281”. However, such phosphors can only be used for a short wave U.V. excitation. Because of their unstable chemical properties and their temperature behavior, they cannot be used in fluorescent lamps.

The influence of lead and copper ions as host lattice component in oxygen dominated compounds, activated by rare earth ions such as Eu²⁺, Ce³⁺ and others, has not been yet described. It should to be expected that the incorporation of lead and/or copper as a host lattice component influences the preferred luminescent-optical properties regarding improved luminescent intensity as well as desirable shifting of emission maxima, color points, and shape of emission spectra and stabilizing of the lattice.

The influence of lead-ions and/or copper-ions as components in the host lattice should show improved luminescent properties for excitation wavelength higher than 360 nm. In this region of wavelength, both ions do not show own radiation transfers due to the energy levels of their electron configuration, so that any kind of exciting radiation cannot be lost.

Lead and copper doped luminescent materials show improved emission intensities compared to luminescent materials having not these components in the host lattice. Furthermore, as a desirable effect of lead and copper doped luminescent materials shows a shifting of the emission wavelength to higher or to lower energies. For compounds containing lead or copper, these ions do not react as activators in broadest sense. However, the use of these ions leads to an influence on the crystal field splitting as well as the covalency.

Lead ions having an ionic radius of 119 pm can substitute the alkaline earth ions Ca having an ionic radius of 100 pm and Sr having an ionic radius of 118 pm very easily. The electro negativity of lead with 1.55 is much higher than that of Ca (1.04) and Sr (0.99). The preparation of substances containing lead is complicated due to the possibility of an oxidation of these ions in reducing atmospheres. For the preparation of lead doped compounds, which need reducing atmosphere, special preparation processes are necessary.

The influence on lead in the crystal field is shown in a generally shifting the emission characteristics depending on the substituted ions. In cases of a substitution of Pb for Sr or Ba in Eu-activated aluminates and/or silicates, the emission maximum should be shifted to longer wavelength due to smaller ionic radii of Pb compared with Ba and Sr ionic radii. That leads to a stronger crystal field in the surrounding of the activator ion.

A similar effect shows the substitution of copper for alkaline earth ions. Here, an additional influence is effective. Due to the higher ionic potential of copper as a quotient of ionic charge and ionic radius compared to the bigger alkaline earth ions, the copper ions can attract the neighboring oxygen ions stronger than the alkaline earth ions. So the substitution of the bigger alkaline earth ions Ca, Sr and Ba by copper leads to a stronger crystal field in the surrounding of the activator ions, too. Thus, the shape of emission bands can be influenced, the shifting of the emission peak to longer wavelength is connected in a broadening of the emission curves for band emission. In addition, it should be possible to increase the intensity of emission by substitution of ions copper and lead. Generally, the shifts of emission peaks to longer as well as to shorter wavelength are desirable in the field of LED lighting. Here, it is necessary to realize a fine tuning to get a special wavelength for desired color points as well as for better brightness of optical devices. By using cations, copper and lead, such a fine tuning should be possible.

It is known that some luminescent materials and phosphors are unstable in water, air humidity, water steam or polar solvents. For instance, aluminates with spinell structure or silicates with orthorhomcic as well as akermanite structures show more or less high sensitivity to water, air humidity, water steam or polar solvents due to high basicity. However, due to a higher covalency and a lower basicity, the incorporation of lead and or copper in a host lattice should improve this behavior of luminescent materials against water, air humidity and polar solvents if substituted for cations having a high basicity.

SUMMARY OF THE INVENTION

In view of the prior art described above, it is an object of the present invention to provide lead and/or copper doped luminescent materials which have a very good possibility to substitute earth alkaline ions by lead and copper with a shifting of the emission bands to longer or shorter wave length, respectively.

Another object of the present invention is to provide luminescent materials containing copper and/or lead with improved luminescent properties and also with improved stability against water, humidity as well as other polar solvents.

An additional object of the present invention is to provide lead and/or copper doped luminescent materials, which give high color temperature range about 2,000K to 8,000K or 10,000K and CRI over 90 in LED.

To achieve these and other objects, as embodied and broadly described herein, luminescent materials for ultraviolet light or visible light excitation comprises lead and/or copper doped chemical compounds containing a rare earth element or other luminescent ions.

The luminescent materials may be composed of one or more compounds of aluminate, silicate, antimonate, germanate/or germanate-silicate, and phosphate.

The aluminate is expressed as follows: a(M′O).b(M″₂O).c(M″X).dAl₂O₃ .e(M′″O).f(M″″₂O₃).g(M′″″_(o)O_(p)).h(M″″″_(x)O_(y)) a(M′O).b(M″₂O).c(M″X).4-a-b-c(M′″O).7(Al₂O₃).d(B₂O₃).e(Ga₂O₃).f(SiO₂).g(GeO₂).h(M″″_(x)O_(y)) and a(M′O).b(M″O).c(Al₂O₃).d(M′″₂O₃).e(M″″O₂).f(M′″″_(x)O_(y))

The silicate is expressed as follows: a(M′O).b(M″O).c(M′″X).d(M′″O₂).e(M″″₂O₃).f(M′″″_(o)O_(p)).g(SiO₂).h(M″″″_(x)O_(y))

The antimonate is expressed as follows: a(M′O).b(M″₂O).c(M″X).d(Sb₂O₅).e(M′″O).f(M″″_(x)O_(y))

The germanate/or germanate-silicate is expressed as follows: a(M′O).b(M″₂O).c(M″X).dGeO₂ .e(M′″O).f(M″″₂O₃).g(M′″″_(o)O_(p)).h(M″″″_(x)O_(y))

The phosphate is expressed as follows: a(M′O).b(M″₂O).c(M″X).dP₂O₅ .e(M′″O).f(M″″₂O₃).g(M′″″O₂).h(M″″″_(x)O_(y))

Meanwhile, the luminescent materials may be used as a converter for the primary long-wave ultraviolet in the range of 300-400 nm and/or blue radiation in the range of 380-500 nm generated from one or more single primary elements within a light emitting device to produce light in the visible region of the spectrum up to a high color rendering index Ra>90.

Furthermore, the luminescent materials may be used in LED as a single compound and/or a mixture of a plurality of single compounds for realizing white light with a color rendering up to Ia.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the present invention will be described in detail.

EXAMPLE 1

Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped aluminates according to the formula as follows: a(M′O).b(M″₂O).c(M″X).dAl₂O₃ .e(M′″O).f(M″″₂O₃).g(M′″″_(o)O_(p)).h(M″″″_(x)O_(y))  (1)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be one or more monovalent elements, for example, Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′″ may be one or more divalent elements, for example, Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M″″ may be one or more trivalent elements, for example, Sc, B, Ga, In, and/or any combination thereof; M′″″ may be Si, Ge, Ti, Zr, Mn, V, Nb, Ta, W, Mo, and/or any combination thereof; M″″″ may be Bi, Sn, Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦2; 0<d≦8; 0<e≦4; 0≦f≦3; 0≦g≦8; 0<h≦2; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5. a(M′O).b(M″₂O).c(M″X).4-a-b-c(M′″O).7(Al₂O₃).d(B₂O₃).e(Ga₂O₃).f(SiO₂).g(GeO₂).h(M″″_(x)O_(y))  (2)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be one or more monovalent elements, for example, Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′″ may be one or more divalent elements, for example, Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M″″ may be Bi, Sn, Sb, Sc, Y, La, In, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and any combination thereof; X may be F; Cl, Br, I, and any combination thereof; 0<a≦4; 0≦b≦2; 0≦c≦2; 0≦d≦1; 0≦e≦1; 0≦f≦1; 0≦g≦1; 0<h≦2; 1≦x≦2; and 1≦y≦5.

The preparation of copper as well as lead doped luminescent materials may be a basic solid state reaction. Pure starting materials without any impurities, e.g. iron, may be used. Any starting material which may transfer into oxides via a heating process may be used to form oxygen dominated phosphors.

EXAMPLES OF PREPARATION:

Preparation of the luminescent material having formula (3) Cu_(0.02)Sr_(3.98)Al₁₄O₂₅:Eu  (3)

Starting materials: CuO, SrCO₃, Al(OH)₃, Eu₂O₃, and/or any combination thereof.

The starting materials in the form of oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, e.g., H₃BO₃. The mixture may be fired in an alumina crucible in a first step at about 1,200° C. for about one hour. After milling the pre-fired materials a second firing step at about 1,450° C. in a reduced atmosphere for about 4 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 494 nm.

TABLE 1 copper doped Eu²⁺-activated aluminate compared with Eu²⁺-activated aluminate without copper at about 400 nm excitation wavelength Copper doped Compound compound without copper Cu_(0.02)Sr_(3.98)Al₁₄O₂₅: Eu Sr₄Al₁₄O₂₅: Eu Luminous density (%) 103.1 100 Wavelength (nm) 494 493

Preparation of the luminescent material having formula (4) Pb_(0.05)Sr_(3.95)Al₁₄O₂₅:Eu  (4)

Starting materials: PbO, SrCO₃, Al₂O₃, Eu₂O₃, and/or any combination thereof.

The starting materials in form of very pure oxides, carbonates, or other components which may decompose thermically into oxides, may be mixed in stoichiometric proportion together with small amounts of flux, for example, H₃BO₃ The mixture may be fired in an alumina crucible at about 1,200° C. for about one hour in the air. After milling the pre-fired materials a second firing step at about 1,450° C. in air for about 2 hours and in a reduced atmosphere for about 2 hours may be followed. Then the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum of from about 494.5 nm.

TABLE 2 lead doped Eu²⁺-activated aluminate compared with Eu²⁺-activated aluminate without lead at about 400 nm excitation wavelength Lead doped Compound compound without lead Ph_(0.05)Sr_(3.95)Al₁₄O₂₅: Eu Sr₄Al₁₄O₂₅: Eu Luminous density (%) 101.4 100 Wavelength (nm) 494.5 493

TABLE 3 optical properties of some copper and/or lead doped aluminates excitable by long wave ultraviolet and/or by visible light and their luminous density in % at 400 nm excitation wavelength Luminous density at Peak 400 nm wave excitation length Peak wave compared of lead/ length of with copper/ copper materials Possible lead not doped doped without excitation compounds materials lead/ Composition range(nm) (%) (nm) copper(nm) Cu_(0.5)Sr_(3.5)Al₁₄O₂₅: Eu 360-430 101.2 495 493 Cu_(0.02)Sr_(3.98)Al₁₄O₂₅: Eu 360-430 103.1 494 493 Pb_(0.05)Sr_(3.95)Al₁₄O₂₅: Eu 360-430 101.4 494.5 493 Cu_(0.01)Sr_(3.99)Al_(13.995)Si_(0.005)O₂₅: Eu 360-430 103 494 492 Cu_(0.01)Sr_(3.395)Ba_(0.595)Al₁₄O₂₅: Eu, Dy 360-430 100.8 494 493 Pb_(0.05)Sr_(3.95)Al_(13.95)Ga_(0.05)O₂₅: Eu 360-430 101.5 494 494

EXAMPLE 2

Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped aluminates according to the formula as follows: a(M′O).b(M″O).c(Al₂O₃).d(M′″₂O₃).e(M″″O₂).f(M′″″_(x)O_(y))  (5)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′″ may be B, Ga, In, and/or any combination thereof; M″″ may be Si, Ge, Ti, Zr, Hf, and/or any combination thereof; M′″″ may be Bi, Sn, Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or any combination thereof; 0<a≦1; 0≦b≦2; 0<c≦8; 0≦d≦1; 0≦e≦1; 0<f≦2; 1≦x<2; and 1≦y≦5.

The luminous peak and density of Example 2 are described in Table 7, which will be shown below.

EXAMPLE OF PREPARATION:

Preparation of the luminescent material having formula (6) Cu_(0.05)Sr_(0.95)Al_(1.9997)Si_(0.0003)O₄:Eu  (6)

Starting materials: CuO, SrCO₃, Al₂O₃, SiO₂, Eu₂O₃, and/or any combination thereof.

The starting materials in the form of, for example, pure oxides and/or as carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, AlF₃. The mixture may be fired in an alumina crucible at about 1,250° C. in a reduced atmosphere for about 3 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 521.5 nm.

TABLE 4 copper doped Eu ²⁺-activated aluminate compared with Eu ²⁺-activated aluminate without copper at about 400 nm excitation wavelength Compound Copper doped compound without copper Cu_(0.05)Sr_(0.95)Al_(1.9997)Si_(0.0003)O₄: Eu SrAl₂O₄: Eu Luminous density (%) 106 100 Wavelength (nm) 521.5 519

Preparation of the luminescent material having formula (7) Cu_(0.12)BaMg_(1.88)Al₁₆O₂₇:Eu  (7)

Starting materials: CuO, MgO, BaCO₃, Al(OH)₃, Eu₂O₃, and/or any combination thereof.

The starting materials in the form of, for example, pure oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, AlF₃. The mixture may be fired in an alumina crucible at about 1,420° C. in a reduced atmosphere for about 2 hours. After that the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum of about 452 nm.

TABLE 5 copper doped Eu²⁺-activated aluminate compared with copper not doped Eu²⁺-activated aluminate at 400 nm excitation wavelength Comparison Copper doped compound without copper Cu_(0.12)BaMg_(1.88)Al₁₆O₂₇: Eu BaMg₂Al₁₆O₂₇: Eu Luminous density 101 100 (%) Wavelength (nm) 452 450

Preparation of the luminescent material having formula (8) Pb_(0.1)Sr_(0.9)Al₂O₄:Eu  (8)

Starting materials: PbO, SrCO₃, Al(OH)₃, Eu₂O₃, and/or any combination thereof.

The starting materials in form of, for example, pure oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, H₃BO₃. The mixture may be fired in an alumina crucible at about 1,000° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at about 1,420° C. in the air for about 1 hour and in a reduced atmosphere for about 2 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 521 nm.

TABLE 6 lead doped Eu ²⁺-activated aluminate compared with Eu ²⁺-activated aluminate without lead at about 400 nm excitation wavelength Lead doped Compound compound without lead Pb_(0.1)Sr_(0.9)Al₂O₄: Eu SrAl₂O₄: Eu Luminous density (%) 102 100 Wavelength (nm) 521 519

Results obtained in regard to copper and/or lead doped aluminates are shown in table 7.

TABLE 7 optical properties of some copper and/or lead doped aluminates excitable by long wave ultraviolet and/or by visible light and their luminous density in % at 400 nm excitation wavelength Peak wave Luminous density at length of Possible 400 nm excitation lead/copper excitation compared with doped Peak wave length of range copper/lead not doped materials materials without Composition (nm) compounds (%) (nm) lead/copper (nm) Cu_(0.05)Sr_(0.95)Al_(1.9997)Si_(0.0003)O₄:Eu 360-440 106 521.5 519 Cu_(0.2)Mg_(0.7995)Li_(0.0005)Al_(1.9)Ga_(0.1)O₄:Eu, Dy 360-440 101.2 482 480 Pb_(0.1)Sr_(0.9)Al₂O₄:Eu 360-440 102 521 519 Cu_(0.05)BaMg_(1.95)Al₁₆O₂₇:Eu, Mn 360-400 100.5 451, 515 450, 515 Cu_(0.12)BaMg_(1.88)Al₁₆O₂₇:Eu 360-400 101 452 450 Cu_(0.01)BaMg_(0.99)Al₁₀O₁₇:Eu 360-400 102.5 451 449 Pb_(0.1)BaMg_(0.9)Al_(9.5)Ga_(0.5)O₁₇:Eu, Dy 360-400 100.8 448 450 Pb_(0.08)Sr_(0.902)Al₂O₄:Eu, Dy 360-440 102.4 521 519 Pb_(0.2)Sr_(0.8)Al₂O₄:Mn 360-440 100.8 658 655 Cu_(0.06)Sr_(0.94)Al₂O₄:Eu 360-440 102.3 521 519 Cu_(0.05)Ba_(0.94)Pb_(0.06)Mg_(0.95)Al₁₀O₁₇:Eu 360-440 100.4 451 449 Pb_(0.3)Ba_(0.7)Cu_(0.1)Mg_(1.9)Al₁₆O₂₇:Eu 360-400 100.8 452 450 Pb_(0.3)Ba_(0.7)Cu_(0.1)Mg_(1.9)Al₁₆O₂₇:Eu, Mn 360-400 100.4 452, 515 450, 515

EXAMPLE 3

Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped silicates according to the formula as follows: a(M′O).b(M″O).c(M′″X).d(M′″₂O).e(M″″₂O₃).f(M′″″_(o)O_(p)).g(SiO₂).h(M″″″_(x)O_(y))  (9)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′″ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M″″ may be Al, Ga, In, and/or any combination thereof; M″″″ may be Ge, V, Nb, Ta, W, Mo, Ti, Zr, Hf, and/or any combination thereof; M″″″ may be Bi, Sn, Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or any combination thereof; X may be F, Cl, Br, I, and any combination thereof; 0<a≦2; 0<b≦8; 0≦c≦4; 0≦d≦2; 0≦e≦2; 0≦f≦2; 0≦g≦10; 0<h≦5; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.

The superior luminous density of Example 3 can be seen below.

EXAMPLE OF PREPARATION:

Preparation of the luminescent material having formula (10) Cu_(0.05)Sr_(1.7)Ca_(0.25)SiO₄:Eu  (10)

Starting materials: CuO, SrCO₃, CaCO₃, SiO₂, Eu₂O₃, and/or any combination thereof.

The starting materials in the form of pure oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH₄Cl. The mixture may be fired in an alumina crucible at about 1,200° C. in an inert gas atmosphere (e.g., N₂ or noble gas) for about 2 hours. Then the material may be milled. After that, the material may be fired in an alumina crucible at about 1,200° C. in a slightly reduced atmosphere for about 2 hours. Then, the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum at about 592 nm.

TABLE 8 copper doped Eu²⁺-activated silicate compared with Eu²⁺-activated silicate without copper at about 400 nm excitation wavelength Compound Copper doped compound without copper Cu_(0.05)Sr_(1.7)Ca_(0.25)SiO₄:Eu Sr_(1.7)Ca_(0.3)SiO₄:Eu Luminous density (%) 104 100 Wavelength (nm) 592 588

Preparation of the Luminescent Material Having Formula (11): Cu_(0.2)Ba₂Zn_(0.2)Mg_(0.6)Si₂O₇:Eu  (11)

Starting materials: CuO, BaCO₃, ZnO, MgO, SiO₂, Eu₂O₃, and/or any combination thereof.

The starting materials in the form of very pure oxides and carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH₄Cl. In a first step the mixture may be fired in an alumina crucible at about 1,100° C. in a reduced atmosphere for about 2 hours. Then the material may be milled. After that the material may be fired in an alumina crucible at about 1,235° C. in a reduced atmosphere for about 2 hours. Then that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 467 nm.

TABLE 9 copper doped Eu²⁺-activated silicate compared with Eu²⁺-activated silicate without copper at 400 nm excitation wavelength Compound Copper doped compound without copper Cu_(0.2)Sr₂Zn_(0.2)Mg_(0.6)Si₂O₇:Eu Sr₂Zn₂Mg_(0.6)Si₂O₇:Eu Luminous density 101.5 100 (%) Wavelength (nm) 467 465

Preparation of the luminescent material having formula (12) Pb_(0.1)BaO_(0.95)Sr_(0.95)Si_(0.998)Ge_(0.002)O₄:Eu  (12)

Starting materials: PbO, SrCO₃, BaCO₃, SiO₂, GeO₂, Eu₂O₃, and/or any combination thereof.

The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH₄Cl. The mixture may be fired in an alumina crucible at about 1,000° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at 1,220° C. in air for 4 hours and in reducing atmosphere for 2 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 527 nm.

TABLE 10 lead doped Eu²⁺-activated silicate compared with Eu²⁺-activated silicate without lead at about 400 nm excitation wavelength Compound Lead doped compound without lead Pb_(0.1)Ba_(0.95)Sr_(0.95)Si_(0.998)Ge_(0.002)O₄:Eu BaSrSiO₄:Eu Luminous density 101.3 100 (%) Wavelength (nm) 527 525

Preparation of the luminescent material having formula (13) Pb_(0.25)Sr_(3.75)Si₃O₈Cl₄:Eu  (13)

Starting materials: PbO, SrCO₃, SrCl₂, SiO₂, Eu₂O₃, and any combination thereof.

The starting materials in the form of oxides, chlorides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH₄Cl. The mixture may be fired in an alumina crucible in a first step at about 1,100° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at about 1,220° C. in the air for about 4 hours and in a reduced atmosphere for about 1 hour may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 492 nm.

TABLE 11 lead doped Eu²⁺-activated chlorosilicate compared with Eu²⁺-activated chlorosilicate without lead at 400 nm excitation wavelength Compound Lead doped compound without lead Pb_(0.25)Sr_(3.75)Si₃O₈Cl₄:Eu Sr₄Si₃O₈Cl₄:Eu Luminous density (%) 100.6 100 Wavelength (nm) 492 490

Results obtained with respect to copper and/or lead doped silicates are shown in table 12.

TABLE 12 optical properties of some copper and/or lead doped rare earth activated silicates excitable by long wave ultraviolet and/or by visible light and their luminous density in % at about 400 nm excitation wavelength Luminous density at Peak wave Possible 400 nm excitation length Peak wave length excitation compared with of lead/copper of materials range copper/lead not doped doped materials without Composition (nm) compounds (%) (nm) lead/copper (nm) Pb_(0.1)Ba_(0.95)Sr_(0.95)Si_(0.998)Ge_(0.002)O₄:Eu 360-470 101.3 527 525 Cu_(0.02)(Ba,Sr,Ca,Zn)_(1.98)SiO₄:Eu 360-500 108.2 565 560 Cu_(0.05)Sr_(1.7)Ca_(0.25)SiO₄:Eu 360-470 104 592 588 Cu_(0.05)Li_(0.002)Sr_(1.5)Ba_(0.448)SiO₄:Gd, Eu 360-470 102.5 557 555 Cu_(0.2)Sr₂Zn_(0.2)Mg_(0.6)Si₂O₇:Eu 360-450 101.5 467 465 Cu_(0.02)Ba_(2.8)Sr_(0.2)Mg_(0.98)Si₂O₈:Eu, Mn 360-420 100.8 440, 660 438, 660 Pb_(0.25)Sr_(3.75)Si₃O₈Cl₄:Eu 360-470 100.6 492 490 Cu_(0.2)Ba_(2.2)Sr_(0.75)Pb_(0.05)Zn_(0.8)Si₂O₈:Eu 360-430 100.8 448 445 Cu_(0.2)Ba₃Mg_(0.8)Si_(1.99)Ge_(0.01)O₈:Eu 360-430 101 444 440 Cu_(0.5)Zn_(0.5)Ba₂Ge_(0.2)Si_(1.8)O₇:Eu 360-420 102.5 435 433 Cu_(0.8)Mg_(0.2)Ba₃Si₂O₈:Eu, Mn 360-430 103 438, 670 435, 670 Pb_(0.15)Ba_(1.84)Zn_(0.01)Si_(0.99)Zr_(0.01)O₄:Eu 360-500 101 512 510 Cu_(0.2)Ba₅Ca_(2.8)Si₄O₁₆:Eu 360-470 101.8 495 491

EXAMPLE 4

Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped antimonates according to the formula as follows: a(M′O).b(M″₂O).c(M′X).d(Sb₂O₅).e(M′″P).f(M″″_(x)O_(y))  (14)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′″ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M″″ may be Bi, Sn, Sc, Y, La, Pr, Sm, Eu, Tb, Dy, Gd, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦4; 0≦d≦8; 0≦e≦8; 0<f≦2; 1≦x≦2; and 1≦y≦5.

EXAMPLES OF PREPARATION:

Preparation of the luminescent material having formula (15) Cu_(0.2)Mg_(1.7)Li_(0.2)Sb₂O₇:Mn  (15)

Starting materials: CuO, MgO, Li₂O, Sb₂O₅, MnCO₃, and/or any combination thereof.

The starting materials in the form of oxides may be mixed in stoichiometric proportion together with small amounts of flux. In a first step the mixture may be fired in an alumina crucible at about 985° C. in the air for about 2 hours. After pre-firing the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,200° C. in an atmosphere containing oxygen for about 8 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 626 nm.

TABLE 13 copper doped antimonate compared with antimonate without copper at about 400 nm excitation wavelength Comparison Copper doped compound without copper Cu_(0.2)Mg_(1.7)Li_(0.2)Sb₂O₇:Mn Mg₂Li_(0.2)Sb₂O₇:Mn Luminous density (%) 101.8 100 Wavelength (nm) 652 650

Preparation of the luminescent material having formula (16) Pb_(0.006)Ca_(0.6)Sr_(0.394)Sb₂O₆  (16)

Starting materials: PbO, CaCO₃, SrCO₃, Sb₂O₅, and/or any combination thereof.

The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux. In a first step the mixture may be fired in an alumina crucible at about 975° C. in the air for about 2 hours. After pre-firing the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,175° C. in the air for about 4 hours and then in an oxygen-containing atmosphere for about 4 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 637 nm.

TABLE 14 lead doped antimonate compared with antimonate without lead at 400 nm excitation wavelength Compound Lead doped compound without lead Pb_(0.006)Ca_(0.6)Sr_(0.394)Sb₂O₆ Ca_(0.6)Sr_(0.4)Sb₂O₆ Luminous density (%) 102 100 Wavelength (nm) 637 638

Results obtained in respect to copper and/or lead doped antimonates are shown in table 15.

TABLE 15 optical properties of some copper and/or lead doped antimonates excitable by long wave ultraviolet and/or by visible light and their luminous density in % at about 400 nm excitation wavelength Luminous density at 400 nm Peak wave excitation length of compared with Peak wave length materials Possible copper/lead not of lead/copper without excitation doped compounds doped materials lead/copper Composition range (nm) (%) (nm) (nm) Pb_(0.2)Mg_(0.002)Ca_(1.798)Sb₂O₆F₂:Mn 360-400 102 645 649 Cu_(0.15)Ca_(1.845)Sr_(0.005)Sb_(1.998)Si_(0.002)O₇:Mn 360-400 101.5 660 658 Cu_(0.2)Mg_(1.7)Li_(0.2)Sb₂O₇:Mn 360-400 101.8 652 650 Cu_(0.2)Pb_(0.01)Ca_(0.79)Sb_(1.98)Nb_(0.02)O₆:Mn 360-400 98.5 658 658 Cu_(0.01)Ca_(1.99)Sb_(1.9995)V_(0.0005)O₇:Mn 360-400 100.5 660 657 Pb_(0.006)Ca_(0.6)Sr_(0.394)Sb₂O₆ 360-400 102 637 638 Cu_(0.02)Ca_(0.9)Sr_(0.5)Ba_(0.4)Mg_(0.18)Sb₂O₇ 360-400 102.5 649 645 Pb_(0.198)Mg_(0.004)Ca_(1.798)Sb₂O₆F₂ 360-400 101.8 628 630

EXAMPLE 5

Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped germanates and/or a germanate-silicates according to the formula as follows: a(M′O).b(M″₂O).c(M″X).dGeO₂ .e(M′″O).f(M″″₂O₃).g(M′″″_(o)O_(p)).h(M″″″_(x)O_(y))  (17)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, and/or any combination thereof; M″″ may be Sc, Y, B, Al, La, Ga, In, and/or any combination thereof; M′″″ may be Si, Ti, Zr, Mn, V, Nb, Ta, W, Mo, and/or any combination thereof; M″″″ may be Bi, Sn, Pr, Sm, Eu, Gd, Dy, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦10; 0<d≦10; 0≦e≦14; 0≦f≦14; 0≦g≦10; 0<h≦2; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.

Example of Preparation:

Preparation of the luminescent material having formula (18) Pb_(0.004)Ca_(1.99)Zn_(0.006)Ge_(0.8)Si_(0.2)O₄:Mn  (18)

Starting materials: PbO, CaCO₃, ZnO, GeO₂, SiO₂, MnCO₃, and/or any combination thereof,

The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH₄Cl. In a first step the mixture may be fired in an alumina crucible at about 1,200° C. in an oxygen-containing atmosphere for about 2 hours. Then, the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,200° C. in oxygen containing atmosphere for about 2 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 655 nm.

TABLE 16 lead doped Mn-activated germanate compared with Mn-activated germinate without lead at about 400 nm excitation wavelength Copper doped compound Comparison without copper Pb_(0.004)Ca_(1.99)Zn_(0.006)Ge_(0.8)Si_(0.2)O₄:Mn Ca_(1.99)Zn_(0.01)Ge_(0.8)Si_(0.2)O₄:Mn Luminous density (%) 101.5 100 Wavelength (nm) 655 657

Preparation of the luminescent material having formula (19) Cu_(0.46)Sr_(0.54)Ge_(0.6)Si_(0.4)O₃:Mn  (19)

Starting materials: CuO, SrCO₃, GeO₂, SiO₂, MnCO₃, and/or any combination thereof.

The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH₄Cl. In a first step the mixture may be fired in an alumina crucible at about 1,100° C. in an oxygen-containing atmosphere for about 2 hours. Then, the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,180° C. in an oxygen-containing atmosphere for about 4 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 658 nm.

TABLE 17 copper doped Mn-activated germanate-silicate compared with Mn-activated germanate-silicate without copper at 400 nm excitation wavelength Compound Copper doped compound without copper Cu_(0.46)Sr_(0.54)Ge_(0.6)Si_(0.4)O₃:Mn SrGe_(0.6)Si_(0.4)O₃:Mn Luminous density (%) 103 100 Wavelength (nm) 658 655

TABLE 18 optical properties of some copper and/or lead doped germanate- silicates excitable by long wave ultraviolet and/or by visible light and their luminous density in % at about 400 nm excitation wavelength Luminous density at 400 nm excitation Peak wave Peak wave Possible compared with length of length of materials excitation copper/lead not lead/copper without range doped doped lead/copper Composition (nm) compounds (%) materials (nm) (nm) Pb_(0.004)Ca_(1.99)Zn_(0.006)Ge_(0.8)Si_(0.2)O₄:Mn 360-400 101.5 655 657 Pb_(0.002)Sr_(0.954)Ca_(1.044)Ge_(0.93)Si_(0.07)O₄:Mn 360-400 101.5 660 661 Cu_(0.46)Sr_(0.54)Ge_(0.6)Si_(0.4)O₃:Mn 360-400 103 658 655 Cu_(0.002)Sr_(0.998)Ba_(0.99)Ca_(0.01)Si_(0.98)Ge_(0.02)O₄:Eu 360-470 102 538 533 Cu_(1.45)Mg_(26.55)Ge_(9.4)Si_(0.6)O₄₈:Mn 360-400 102 660 657 Cu_(1.2)Mg_(26.8)Ge_(8.9)Si_(1.1)O₄₈:Mn 360-400 103.8 670 656 Cu₄Mg₂₀Zn₄Ge₅Si_(2.5)O₃₈F₁₀:Mn 360-400 101.5 658 655 Pb_(0.001)Ba_(0.849)Zn_(0.05)Sr_(1.1)Ge_(0.04)Si_(0.96)O₄:Eu 360-470 101.8 550 545 Cu_(0.05)Mg_(4.95)GeO₆F₂:Mn 360-400 100.5 655 653 Cu_(0.05)Mg_(3.95)GeO_(5.5)F:Mn 360-400 100.8 657 653

EXAMPLE 6

Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped phosphates according to the formula as follows: a(M′O).b(M″₂O).c(M″X).dP₂O₅ .e(M′″O).f(M″″₂O₃).g(M′″″O₂).h(M″″″_(x)O_(y))  (20)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′″ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M″″ may be Sc, Y, B, Al, La, Ga, In, and/or any combination thereof, M′″″ may be Si, Ge, Ti, Zr, Hf; V, Nb, Ta, W, Mo, and/or any combination thereof; M″″″ may be Bi, Sn, Pr, Sm, Eu, Gd, Dy, Ce, Tb, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦12; 0≦c≦16; 0<d≦3; 0≦e≦5; 0≦f≦3; 0≦g≦2; 0<h≦2; 1≦x≦2; and 1≦y≦5.

The luminescent materials comprising the lead and/or copper doped phosphates may be used as compounds for ultraviolet light in a light emitting device.

EXAMPLES OF PREPARATION:

Preparation of the luminescent material having formula (21) Cu_(0.02)Ca_(4.98)(PO₄)₃Cl:Eu  (21)

Starting materials: CuO, CaCO₃, Ca₃(PO₄)₂, CaCl₂, Eu₂O₃, and/or any combination thereof,

The starting materials in the form of oxides, phosphates, and/or carbonates and chlorides may be mixed in stoichiometric proportions together with small amounts of flux. The mixture may be fired in an alumina crucible at about 1,240° C. in reducing atmosphere for about 2 hours. After that the material may be milled, washed, dried and sieved. The luminescent material may have an emission maximum at about 450 nm.

TABLE 19 copper doped Eu²⁺-activated chlorophosphate compared with Eu²⁺-activated chlorophosphate without copper at about 400 nm excitation wavelength Compound Copper doped compound without copper Cu_(0.02)Ca_(4.98)(PO₄)₃Cl:Eu Ca₅(PO₄)₃Cl:Eu Luminous density (%) 101.5 100 Wavelength (nm) 450 447

TABLE 20 copper and/or lead doped phosphates excitable by long wave ultraviolet and/or by visible light and their luminous density in % at about 400 nm excitation wavelength Luminous density at 400 nm excitation compared Peak wave length Peak wave length Possible with copper/lead not of lead/copper of materials excitation doped compounds doped materials without Composition range (nm) (%) (nm) lead/copper (nm) Cu_(0.02)Sr_(4.98)(PO₄)₃Cl:Eu 360-410 101.5 450 447 Cu_(0.2)Mg_(0.8)BaP₂O₇:Eu, Mn 360-400 102 638 635 Pb_(0.5)Sr_(1.5)P_(1.84)B_(0.16)O_(6.84):Eu 360-400 102 425 420 Cu_(0.5)Mg_(0.5)Ba₂(P,Si)₂O₈:Eu 360-400 101 573 570 Cu_(0.5)Sr_(9.5)(P,B)₆O₂₄Cl₂:Eu 360-410 102 460 456 Cu_(0.5)Ba₃Sr_(6.5)P₆O₂₄(F,Cl)₂:Eu 360-410 102 443 442 Cu_(0.05)(Ca,Sr,Ba)_(4.95)P₃O₁₂Cl:Eu, Mn 360-410 101.5 438, 641 435, 640 Pb_(0.1)Ba_(2.9)P₂O₈:Eu 360-400 103 421 419

Lead and/or copper doped luminescent materials can be act as converter for light emitting devices, such as ultraviolet as well as blue emitting LEDs, back lights and painting pigments. They can convert the excitation wavelength from the ultraviolet and blue light to longer visible wavelength. For all color temperatures as well as for all color coordinates inside of the white light coordinates color mixture can be found. That is caused by the different emission colors corresponding to the RGB principle by using different kinds of luminescent materials. 

1. A luminescent material for an LED, comprising: a compound including a host lattice and a luminescent ion, wherein the host lattice comprises copper ions and oxygen, and wherein the compound has the formula a(M′O).b(M″O).c(Al₂O₃).d(M′″₂O₃).e(M″″O₂).f(M′″″_(x)O_(y)) wherein M′ is Cu, or a combination of Cu and Pb; M″ is Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, or any combination of thereof; M′″ is B, Ga, In, or any combination thereof; M″″ is Si, Ge, Ti, Zr, Hf, or any combination thereof; M′″″ is a combination of at least one of Y, Gd, and Lu and at least one of Bi, Sn, Sb, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb; 0<a≦1; 0≦b≦2; 0<c≦8; 0≦d≦1; 0≦e≦1; 0<f≦2; 1≦x≦2; and 1≦y≦5.
 2. The luminescent material of claim 1, wherein the host lattice comprises lead ions.
 3. The luminescent material of claim 1, wherein the luminescent ion comprises at least one element of Eu or Ce.
 4. The luminescent material of claim 1, wherein the compound is suitable for emitting light upon excitation with near ultraviolet (UV) or visible light. 